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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.42: Poster

Monday, March 26, 2012, 17:00–19:00, Poster B

Interaction of Ultrashort XUV pulses with Bulk Magnesium and Copper — •Naira Grigoryan, Fairoja Cheenicode Kabeer, Eeuwe S. Zijlstra, and Martin E. Garcia — Theoretical Physics, University Kassel, Heinrich-Plett-Str. 40, Kassel, Germany

The excitation of a material with very intense femtosecond XUV pulses first leads to an exotic state characterized by a very high density of core holes (about 1 core hole per atom) and relatively warm electrons [Nagler et al.]. The next step is the formation of warm dense matter. In this work we perform all-electron ab initio calculations in order to determine the main pathways from solid to warm dense magnesium and copper. Surprisingly, frozen phonon calculations for the transverse and longitudinal modes at the M point lying at the boundary of the Brillouin zone of magnesium reveal hardening as a function of the electronic temperature in the laser-excited state for LO, LA, TO(perp), TA(perp) and softening for TO(parallel), TA(parallel), and hardening for all modes, as a function of temperature, in the presence of a core-hole. For the copper TA mode at the X point we also find hardening as a function of the electronic temperature in the laser-excited state and in the presence of a core-hole, which is opposite to the behavior of most materials, which soften in at least some directions when electrons are excited.